PURPOSE: To determine the clinical usefulness of MR imaging to screen
for vascular compression of the lateral medulla, considered by some to
be responsible for neurogenic hypertension. METHODS: MR images and cl
inical records of 120 adults who had received brain MR imaging for any
reason were divided into two groups: group 1 (n = 60) consisted of pa
tients with essential hypertension and group 2 (n = 60) included patie
nts who lacked a diagnosis of hypertension, No patient manifested symp
tomatic cranial neuralgias. The root entry zone of cranial nerves IX a
nd X into the left lateral medulla was examined by MR imaging for prox
imity to the ipsilateral vertebral artery or its branches. Images lack
ing any contact between visible vascular structures and the root entry
zone were recorded as normal, Vascular compression was graded accordi
ng to the degree of proximity to the root entry zone. Lateral medullar
y contact only (grade I), contact and depression (grade II), or lower
brain ste;n displacement or rotation (grade III) of the root entry zon
e were recorded in both hypertensive and normotensive patients. Among
hypertensive patients, additional data were gathered from electrocardi
ographic, echocardiographic, and urinary protein reports. RESULTS: We
found compression in 34 (57%) of the patients from group 1 and in 33 (
55%) of the patients from group 2, Compressions in group 1 were grade
1 in 22 (37%) of the patients, grade II in 8 (13%), and grade III in 4
(7%). Among group 2 patients, grade I compressions were found in 27 (
45%), grade II in 4 (7%), and grade III in 2 (3%). There were no stati
stically significant differences in MR findings between the two groups
, Among group 1 patients, MR grading did not predict end-organ changes
in the heart (left axis deviation and left ventricular hypertrophy) o
r kidneys (proteinuria). CONCLUSION: Vascular compression of the root
entry zone of cranial nerves IX and X into the left lateral medulla is
not an adequate lesion to produce systemic hypertension. This finding
is as common among normotensive patients as among hypertensive popula
tions. Neither the presence nor the severity of changes in the root en
try zone on MR images increases the occurrence of common end-organ res
ponses in the heart or kidneys among hypertensive patients. MR screeni
ng is not warranted among hypertensive patients lacking symptomatic cr
anial neuralgias.